The present invention relates to burners capable of utilizing relatively low pressure air sources and still provide a long, narrow flame.
Burners are used in many applications in which a long, narrow flame is desirable. For example, unwanted water is often removed from crude oil in the field by placing the crude oil in a large vat, and heating the oil by projecting a flame into a tube in the bottom of the vat to vaporize the water. A relatively long flame is desirable to distribute heat throughout the tube. Ofter crude oil itself is used in the combustible mixture, and excess crude oil must not splash on the walls of the tube because it would cause an unwanted build up of carbon deposits. Accordingly, the flame should not only be long but must be quite narrow as well.
The typical solution in applications requiring a long, narrow flame such as that described above is to utilize a burner in which high pressure air is used to feed combustion (primary air) and to atomize the combustible material (atomizing air). Such high pressure air both increases the length of the flame and decreases its width. However, the provision of air at high pressures requires large capacity blowers, both for primary air and atomizing air. As a result, large side draft fans are typically used which are expensive, noisy and require frequent maintenance, a particular problem in many field applications.
It would be desirable to provide a burner which generates a long, narrow flame, but operates off of relatively low pressure air sources. Such a system could use a simply centrifugal fan for its primary air supply, and a smaller side draft fan for atomizing air. Such fans would be less noisy, and would have a much lower maintenance requirement. However, in the past, it has been found difficult to generate a long, narrow flame using such low pressure air supplies. Moreover, attempts to lengthen the flame provided by such a burner have generally resulted in unstable flames, which may extinguish themselves, or unwanted vibrations resulting from cyclic variations in the flame front, often called a "diaphragm" effect.